Electrical Catechism: An Introductory Treatise on Electricity and Its Uses |
Common terms and phrases
adiabatic alternating current altitude ammeter amperes arc lamps armature atmosphere axis battery becomes belt boundary surface brushes carbon causes cell charged circuit component computation condensation condition conductor connected considered constant coördinates copper corresponding curve cyclone direct current direction disks dynamo earth earth's surface electrodynamometer electromotive force energy equal equation field coils flow fluid friction function fuse galvanometer give given heat inch increase indicated instrument insulated iron lines of force liquid load machine magnetic field measured millimetres mixture motion motor negative obtain occur Ohm's law ohms particles pass plane plates pole positive potential potential temperature pressure quantity ratio region resistance rheostat ring rotation saturated shunt side square static electricity switch temperature terminals tion unit vapor velocity vertical voltage voltmeter volts vortex filaments watts waves wind wire zero zinc ду дх
Popular passages
Page 55 - As a unit of resistance, the international ohm, which is based upon the ohm equal to 10" units of resistance of the CGS system of electromagnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grams in mass, of a constant cross-sectional area and of the length of 106.3 centimetres.
Page 56 - As a unit of current, the international ampere, which is one-tenth of the unit of current of the CGS system of electro-magnetic units, and which is represented sufficiently well for practical use by the unvarying current, which, when passed through a solution of nitrate of silver in water in accordance with accompanying specifications,1 deposits silver at the rate of o.ooi 1 1 8 of a gramme per second.
Page 56 - As a unit of electro-motive force, the international volt, " which is the electro-motive force that, steadily applied to a " conductor whose resistance is one international ohm, will '• produce a current of one international ampere...
Page 58 - For compressible flow this becomes: where y is the ratio of the specific heat at constant pressure to that at constant volume and M is the local Mach number (see below for definition), y has a mean value of 1-4 for air.
Page 57 - As a unit of quantity, the international coulomb, which is the quantity of electricity transferred by a current of one international ampere in one second. As a unit of capacity, the international farad, which is the capacity of a condenser charged to a potential of one international volt by one international coulomb of electricity.
Page 92 - The lower limit is specified for rubber-covered wires to prevent gradual deterioration of the high insulations by the heat of the wires, but not from fear of igniting the insulation. The question of drop is not taken into consideration in the above tables.
Page 55 - ... represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice fourteen and four thousand five hundred...
Page 56 - The unit of current shall be what is known as the international ampere, which is one-tenth of the unit of current of the centimeter-gram-second system of electro-magnetic units, and Ampere is the practical equivalent of the unvarying current, which, when passed through a solution of nitrate of silver in water in accordance with standard specifications, deposits silver at the rate of one thousand one hundred and eighteen millionths of a gram per second.
Page 287 - According to this law, as is well known, there is no limit to the height of the atmosphere. Before proceeding further, let us pause for a moment to consider how the density at various heights would be affected by a small change of temperature, altering a for a,, the whole quantity of air and there•From the London, Edinburgh and Dublin Phil.
Page 292 - Laplace's theory, viz. 33 x 10s cm./sec., we shall find 4 x 109 On the same basis, T, = 13'7 hours. It must, however, be remarked that the suitability of this value of a is very doubtful, and that the suppositions of the present paper are inconsistent with the use of Laplace's correction to Newton's theory of sound propagation. In a more elaborate treatment a difficult question would present itself as to whether the heat and cold developed during atmospheric vibrations could be supposed to remain...